Gas cluster ion beam process for opening conformal layer in a high aspect ratio contact via

ABSTRACT

A method for opening a conformal layer at the bottom of a contact via on a substrate is described. The method includes providing a substrate having a first layer with a via pattern formed therein and a second layer conformally deposited on the first layer and within the via pattern to establish a contact via pattern characterized by an initial mid-critical dimension (CD). The method further includes etching through the second layer at the bottom of the contact via pattern to extend the contact via pattern through the second layer and form a contact via while retaining at least part of the second layer on the top surface of the first layer, the corner at the entrance to the via pattern, and the sidewalls of the via pattern, wherein the etching is performed by irradiating the substrate with a gas cluster ion beam (GCIB) according to a GCIB etching process.

FIELD OF INVENTION

The invention relates to gas cluster ion beam (GCIB) processing.

DESCRIPTION OF RELATED ART

Typically, during fabrication of an integrated circuit (IC),semiconductor production equipment utilize a (dry) plasma etch processto remove or etch material along fine lines or within vias or contactspatterned on a semiconductor substrate. The success of the plasma etchprocess requires that the etch chemistry includes chemical reactantssuitable for selectively etching one material while etching anothermaterial at a substantially lesser rate. Furthermore, the success of theplasma etch process requires that acceptable profile control may beachieved while applying the etch process uniformly to the substrate.However, in some etch applications, conventional etch processes may notachieve acceptable profile control that is uniformly applied across thesubstrate.

SUMMARY OF THE INVENTION

Embodiments of the invention relate to GCIB processing. In particular,embodiments of the invention relate to GCIB etch processing.Furthermore, embodiments of the invention relate to GCIB etch processingof various materials to achieve target etch process metrics.

According to one embodiment, a method for opening a conformal layer atthe bottom of a contact via on a substrate is described. The methodincludes providing a substrate having a first layer with a via patternformed therein and a second layer conformally deposited on the firstlayer and within the via pattern to establish a contact via patterncharacterized by an initial mid-critical dimension (CD). The methodfurther includes etching through the second layer at the bottom of thecontact via pattern to extend the contact via pattern through the secondlayer and form a contact via while retaining at least part of the secondlayer on the top surface of the first layer, the corner at the entranceto the via pattern, and the sidewalls of the via pattern, wherein theetching is performed by irradiating the substrate with a gas cluster ionbeam (GCIB) according to a GCIB etching process.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIGS. 1A through 1E provide schematic illustrations of methods foropening a conformal layer at the bottom of a contact via on a substrateaccording to an embodiment;

FIG. 2 is a flow chart illustrating a method for opening a conformallayer at the bottom of a contact via on a substrate according to anembodiment;

FIG. 3A provides a schematic graphical illustration of a beam energydistribution function for a GCIB;

FIG. 3B provides a schematic graphical illustration of a beam angulardistribution function for a GCIB;

FIGS. 4A through 4L graphically depict exemplary data for etchingmaterial on a substrate;

FIG. 5 is an illustration of a GCIB processing system;

FIG. 6 is another illustration of a GCIB processing system;

FIG. 7 is yet another illustration of a GCIB processing system;

FIG. 8 is an illustration of an ionization source for a GCIB processingsystem; and

FIG. 9 is an illustration of another ionization source for a GCIBprocessing system.

DETAILED DESCRIPTION OF SEVERAL EMBODIMENTS

Methods for etching layers, including high aspect ratio (HAR) contacts,on a substrate using gas cluster ion beam (GCIB) processing aredescribed in various embodiments. One skilled in the relevant art willrecognize that the various embodiments may be practiced without one ormore of the specific details, or with other replacement and/oradditional methods, materials, or components. In other instances,well-known structures, materials, or operations are not shown ordescribed in detail to avoid obscuring aspects of various embodiments ofthe invention. Similarly, for purposes of explanation, specific numbers,materials, and configurations are set forth in order to provide athorough understanding of the invention. Nevertheless, the invention maybe practiced without specific details. Furthermore, it is understoodthat the various embodiments shown in the figures are illustrativerepresentations and are not necessarily drawn to scale.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure, material, orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the invention, but does not denote thatthey are present in every embodiment. Thus, the appearances of thephrases “in one embodiment” or “in an embodiment” in various placesthroughout this specification are not necessarily referring to the sameembodiment of the invention. Furthermore, the particular features,structures, materials, or characteristics may be combined in anysuitable manner in one or more embodiments. Various additional layersand/or structures may be included and/or described features may beomitted in other embodiments.

“Substrate” as used herein generically refers to the object beingprocessed in accordance with the invention. The substrate may includeany material portion or structure of a device, particularly asemiconductor or other electronics device, and may, for example, be abase substrate structure, such as a semiconductor wafer or a layer on oroverlying a base substrate structure such as a thin film. Thus,substrate is not intended to be limited to any particular basestructure, underlying layer or overlying layer, patterned orunpatterned, but rather, is contemplated to include any such layer orbase structure, and any combination of layers and/or base structures.The description below may reference particular types of substrates, butthis is for illustrative purposes only and not limitation.

As described in part above, etch rate, etch selectivity, profilecontrol, including CD (critical dimension) control, and surfaceroughness provide, among other process results, essential metrics fordetermining successful pattern etching. As an example, when transferringa feature pattern into a material layer on a substrate, it is importantto selectively etch one material at a rate sufficient for adequateprocess throughput, while controlling the pattern profile and surfaceroughness of pattern surfaces as well as adjacent surfaces. Furthermore,it is important to control the etch rate, etch selectivity, and etchprofile uniformly for all feature patterns formed in the material layeron the substrate, and/or spatially adjust the control of theseparameters for feature patterns formed in the material layer on thesubstrate.

As an example, etch profile control is critically important whenperforming a high aspect ratio (HAR) contact etch in memory structures,such as three-dimensional (3D) flash memory. During the opening of theHAR contact, conventional etch processes, such as reactive ion etch(RIE) processes, fail to produce acceptable results. In particular, RIEcauses critical dimension (CD) loss for the contact via and severecorner erosion at the entrance to the contact via, either of which isunacceptable and leads to poor electrical properties once the contact isfilled.

Therefore, according to various embodiments, methods for opening aconformal layer at the bottom of a contact via on a substrate aredescribed. Referring now to the drawings wherein like reference numeralsdesignate corresponding parts throughout the several views, FIGS. 1Athrough 1E graphically depict various methods for opening a conformallayer at the bottom of a contact via. Furthermore, FIG. 2 provides aflow chart 20 illustrating a method for etching various materials on asubstrate according to an embodiment.

The method illustrated in flow chart 20 begins in 21 with providing asubstrate 11 having a first layer 12 with a via pattern 14 formedtherein (see FIG. 1A) and a second layer 13A (see FIG. 1B) conformallydeposited on the first layer 12 and within the via pattern 14. Thesecond layer 13A conforms to the first layer 12, extends along a topsurface 12A of the first layer 12, wraps over a corner 12B at anentrance 14A to the via pattern 14, and penetrates into the via pattern14 while conforming to the sidewalls 12C and the bottom 12D of the viapattern 14 to partially establish a contact via pattern 15A. As shown inFIG. 1B, the contact via pattern 15A is characterized by an initialmid-critical dimension (CD) 16AM measured at approximately mid-depth ofthe contact via pattern 15A, and an initial top-CD 16AT measured atapproximately the top of the contact via pattern 15A. Further, thecontact via pattern 15A may be characterized by an initial cornerprofile 13AC for the second layer 13A as it wraps over corner 12B of viapattern 14.

The substrate 11 may include a bulk silicon substrate, a single crystalsilicon (doped or un-doped) substrate, a semiconductor-on-insulator(SOI) substrate, or any other semiconductor substrate containing, forexample, Si, SiC, SiGe, SiGeC, Ge, GaAs, InAs, InP, as well as otherIII/V or II/VI compound semiconductors, or any combination thereof(Groups II, III, V, VI refer to the classical or old IUPAC notation inthe Periodic Table of Elements; according to the revised or new IUPACnotation, these Groups would refer to Groups 2, 13, 15, 16,respectively). Substrate 11 can be of any size, for example, a 200 mm(millimeter) substrate, a 300 mm substrate, a 450 mm substrate, or aneven larger substrate.

The first layer 12 may include an oxide, such as a layer of silicondioxide (SiO₂), or more generally, SiO_(x), wherein x is a positive realnumber. The first layer 12 may include a dopant or other materialintroduced therein. The first layer 12 may include a low dielectricconstant (low-k) layer.

The second layer 13A may include an oxide-nitride-oxide (ONO) layer. Forexample, the second layer 13A may include a multi-layer film containingsilicon oxide, silicon nitride, and silicon oxide. The second layer 13Amay be deposited using one or more deposition processes. The one or moredeposition processes may include chemical vapor deposition (CVD), plasmaenhanced CVD, atomic layer deposition (ALD), plasma enhanced ALD, orGCIB deposition processes, or any combination of two or more thereof.The thickness of the second layer 13A may range from about 5 nm(nanometers) to about 100 nm. Alternatively, the thickness of the secondlayer 13A may range from about 10 nm to about 50 nm. Alternatively yet,the thickness of the second layer 13A may range from about 20 nm toabout 40 nm. For example, the thickness of the second layer 13A may beabout 25 nm to about 35 nm, or about 30 nm.

In 22 and as shown in FIG. 1D, the second layer 13A is etched to extendthe contact via pattern 15A at the bottom 12D of the via pattern 14through the second layer 13A and form a contact via 15C. After formingthe contact via 15C, at least a portion 13C of the second layer 13Aremains on the top surface 12A of the first layer 12, the corner 12B atthe entrance 14A to the via pattern 14, and the sidewalls 12C of the viapattern 14. The partial etching of the second layer 13A to form contactvia 15C is performed by irradiating substrate 11 with a gas cluster ionbeam (GCIB) according to a GCIB etching process.

The contact via 15C may be characterized by an aspect ratio of 5:1 orgreater, wherein the aspect ratio is measured as the ratio between adepth of the contact via 15C following the GCIB etching process and afinal mid-CD 16CM of the contact via 15C. Furthermore, the aspect ratiomay be 10:1 or greater.

Furthermore, during formation of the contact via 15C, it is desirablethat the CD loss in the contact via 15C and the erosion of the cornerprofile 13CC is kept to a minimum. As shown in FIG. 1D, the CD loss maybe measured as the difference between the final mid-CD 16CM for thecontact via 15C and the initial mid-CD 16AM for the contact via pattern15A. Preferably, the CD loss has a value of 10 nm or less, and morepreferably, the CD loss has a value of 5 nm or less, or 4 nm or less, or3 nm or less, or most preferably, 2 nm or less.

Additionally, as shown in FIG. 1E, the amount of erosion at the corner13CC may be quantified by measuring the difference between a finaltop-CD 16CT for the contact via 15C and the initial top-CD 16AT for thecontact via pattern 15A. Preferably, the difference in top-CD has avalue of 10 nm or less, and more preferably, the difference in top-CDhas a value of 5 nm or less, or 4 nm or less, or 3 nm or less, or mostpreferably, 2 nm or less. Another measure of the performance for theGCIB etching process is the change in thickness 16CF of the second layer13A on the top surface 12A of the first layer 12. Preferably, the changein thickness 16CF has a value of 10 nm or less. Contact via patterningcan achieve the aforementioned specifications when using a GCIB etchingprocess, as will be described in greater detail below.

However, as illustrated in FIG. 1C when using a conventional etchingprocess, such as RIE, to extend the contact via pattern 15A through thesecond layer 13A and form a contact via 15B while retaining at least aportion 13B of the second layer 13A, the end result is unsatisfactory,and generally, unacceptable for current and future electronic devices.As noted in the description of the related art, profile and CD controlare important parameters that conventional etch processes oftentimescannot achieve to the satisfaction of the device maker. In particular,with contact via patterning for memory fabrication, the CD loss may beexcessive, and the erosion of the corner profile 13BC at the entrance14A to the via pattern 14 can be severe relative to the initial cornerprofile 13AC. In the former, the CD loss may exceed 10 nm. In thelatter, the erosion of the corner profile 13BC may be such that one ormore sub-layers of the ONO layer constituting the second layer 13B arepenetrated, or that the second layer 13B is consumed entirely at thecorner 12B, thus exposing the first layer 12. In this case, thedifference between a final top-CD 16BT for the contact via 15B and theinitial top-CD 16AT for the contact via pattern 15A may exceed 10 nm.

To achieve the GCIB etching process and results illustrated anddescribed in FIGS. 1A, 1B, 1D, 1E, and 2, the GCIB etching processincludes disposing a substrate, such as substrate 11, within a gascluster ion beam (GCIB) processing system, and maintaining areduced-pressure environment around a substrate holder for holding thesubstrate in the GCIB processing system. The GCIB processing system mayinclude any one of the GCIB processing systems (100, 100′ or 100″)described below in FIGS. 5, 6 or 7, or any combination thereof.

The GCIB etching process proceeds with holding the substrate 11 securelywithin the reduced-pressure environment of the GCIB processing system.The temperature of substrate 11 may or may not be controlled. Forexample, substrate 11 may be heated or cooled during a GCIBpre-treatment, etching, or post-treatment process.

When performing the GCIB etching process, one or more target etchprocess metrics are selected. As noted above and discussed in greaterdetail below, the target etch process metrics may include an etch rateof the first layer, an etch rate of the second layer, an etch rate ofthe substrate, an etch selectivity between the first layer and thesecond layer, an etch selectivity between the second layer and thesubstrate, a surface roughness of the second layer, a surface roughnessof the substrate, an etch profile of the contact via, a CD of thecontact via, and a corner profile of the contact via. One or more GCIBproperties of a GCIB process condition may be set for operating the GCIBprocessing system to perform the GCIB etching process and achieve theone or more target etch process metrics. In addition to etch processmetrics, other metrics may be used, including electrical test metricsfollowing completion of the contact fill.

In the GCIB processing system, a gas cluster ion beam (GCIB) is formedfrom a pressurized gas containing at least one etching gas. The at leastone etching gas may include a halogen element. The at least one etchinggas may include a halogen element and one or more elements selected fromthe group consisting of C, H, N, and S.

For example, the at least one etching gas may include F₂, Cl₂, Br₂, NF₃,or SF₆. Additionally, for example, the at least one etching gas mayinclude a halide, such as HF, HCl, HBr, or HI. Furthermore, for example,the at least one etching gas may include a halomethane, such as amono-substituted halomethane (e.g., CH₃F, CH₃Cl, CH₃Br, CH₃I), adi-substituted halomethane (e.g., CH₂F₂, CH₂ClF, CH₂BrF, CH₂FI, CH₂Cl₂,CH₂BrCl, CH₂ClI, CH₂Br₂, CH₂BrI, CH₂I₂), a tri-substituted halomethane(e.g., CHF₃, CHClF₂, CHBrF₂, CHF₂I, CHCl₂F, CHBrClF, CHClFI, CHBr₂F,CHBrFI, CHFI₂, CHCl₃, CHBrCl₂, CHCl₂I, CHBr₂Cl, CHBrClI, CHClI₂, CHBr₃,CHBr₂I, CHBrI₂, CHI₃), or a tetra-substituted halomethane (e.g., CF₄,CClF₃, CBrF₃, CF₃I, CCl₂F₂, CBrClF₂, CClF₂I, CBr₂F₂, CBrF₂I, CF₂I₂,CCl₃F, CBrCl₂F, CCl₂FI, CBr₂ClF, CBrClFI, CClFI₂, CBr₃F, CBr₂FI, CBrFI₂,CFI₃, CCl₄, CBrCl₃, CCl₃I, CBr₂Cl₂, CBrCl₂I, CCl₂I₂, CBr₃Cl, CBr₂ClI,CBrClI₂, CClI₃, CBr₄, CBr₃I, CBr₂I₂, CBrI₃, Cl₄).

To form the GCIB, constituents of the etching gas should be selectedthat exist in a gaseous phase either alone or in combination with acarrier gas (e.g., a noble gas element or nitrogen) at relatively highpressure (e.g., a pressure of one atmosphere or greater).

In one embodiment, when etching a Si-containing and/or Ge-containingmaterial, the at least one etching gas includes a halogen elementselected from the group consisting of F, Cl, and Br. The at least oneetching gas may further include C, or H, or both C and H. For example,the at least one etching gas may include a halide or a halomethane.Additionally, for example, the at least one etching gas may include SF₆,NF₃, F₂, Cl₂, Br₂, HF, HCl, HBr, CClF₃, CBrF₃, CHClF₂, or C₂ClF₅, or anycombination of two or more thereof.

In another embodiment, when etching a Si-containing and/or Ge-containingmaterial, the at least one etching gas includes two different halogenelements. A first halogen element may be selected from the groupconsisting of Cl and Br, and the second halogen element may include F.The at least one etching gas may further include C, or H, or both C andH. For example, the at least one etching gas may include a halomethane.Additionally, for example, the at least one etching gas may includeCClF₃, CBrF₃, CHClF₂, or C₂ClF₅, or any combination of two or morethereof.

In another embodiment, when etching a Si-containing material having Siand one or more elements selected from the group consisting of O, C, N,and Ge, the at least one etching gas includes C, H, and a halogenelement. For example, the etching gas may include a halomethane.Additionally, for example, the etching gas may include CH₃F, CH₃Cl,CH₃Br, CHF₃, CHClF₂, CHBrF₂, CH₂F₂, CH₂ClF, CH₂BrF, CHCl₂F, CHBr₂F,CHCl₃, CHBrCl₂, CHBr₂Cl, or CHBr₃, or any combination of two or morethereof.

In another embodiment, when etching an ONO layer to pattern a HARcontact via, the etching gas may include CHF₃. In another embodiment,when etching an ONO layer to pattern a HAR contact via, the etching gasmay include CHF₃ and an oxygen-containing gas. The oxygen-containing gasmay include O₂, CO, CO₂, NO, NO₂, or N₂O. In yet another embodiment,when etching an ONO layer to pattern a HAR contact via, the etching gasmay include CHF₃ and O₂. A CHF₃-based GCIB etching process can achievethe target etch process metrics noted above.

The at least one etching gas may include a first etching gas and asecond etching gas. In one embodiment, the first etching gas contains Clor Br, and the second etching gas contains F. For example, the firstetching gas may contain Cl₂, and the second etching gas may contain NF₃.In another embodiment, the first etching gas contains a halomethane orhalide, and the second etching gas contains F, Cl, or Br. In anotherembodiment, the first etching gas contains C, H, and a halogen element,and the second etching gas contains F, Cl, or Br. For example, the firstetching gas may contain CHF₃, CHCl₃, or CHBr₃, and the second etchinggas may contain NF₃ or Cl₂. The first etching gas and the second etchinggas may be continuously introduced to the GCIB. Alternatively, the firstetching gas and the second etching gas may be alternatingly andsequentially introduced to the GCIB.

The pressurized gas may further include a compound containing a halogenelement; a compound containing F and C; a compound containing H and C;or a compound containing C, H, and F, or any combination of two or morethereof. Additionally, the pressurized gas may further include achlorine-containing compound, a fluorine-containing compound, or abromine-containing compound. Additionally, the pressurized gas mayfurther include a compound containing one or more elements selected fromthe group consisting of C, F, H, Cl, and Br. Additionally yet, thepressurized gas may further include a silicon-containing compound, agermanium-containing compound, a nitrogen-containing compound, anoxygen-containing compound, or a carbon-containing compound, or anycombination of two or more thereof. Furthermore, the pressurized gas mayfurther include one or more elements selected from the group consistingof B, C, H, Si, Ge, N, P, As, O, S, F, Cl, and Br. Further yet, thepressurized gas may further include He, Ne, Ar, Kr, Xe, O₂, CO, CO₂, N₂,NO, NO₂, N₂O, NH₃, F₂, HF, SF₆, or NF₃, or any combination of two ormore thereof.

Even further yet, the GCIB may be generated from a pressurized gas thatincludes at least one dopant, or film forming constituent for depositingor growing a thin film, or any combination of two or more thereof.

In another embodiment, the GCIB may be generated by alternatingly andsequentially using a first pressurized gas containing an etch gas and asecond pressurized gas containing a film forming gas. In yet otherembodiments, a composition and/or a stagnation pressure of the GCIB maybe adjusted during the etching.

As noted above, one or more GCIB properties of a GCIB process conditionfor the GCIB are set to achieve the one or more target etch processmetrics. To achieve the target etch process metrics noted above, such asetch rate, etch selectivity, surface roughness control, profile control,etc., the GCIB may be generated by performing the following: selecting abeam acceleration potential, one or more beam focus potentials, and abeam dose; accelerating the GCIB according to the beam accelerationpotential; focusing the GCIB to according to the one or more beam focuspotentials; and irradiating the accelerated GCIB onto at least a portionof the substrate according to the beam dose.

Furthermore, in addition to these GCIB properties, a beam energy, a beamenergy distribution, a beam angular distribution, a beam divergenceangle, a stagnation pressure, a stagnation temperature, a mass flowrate, a cluster size, a cluster size distribution, a beam size, a beamcomposition, a beam electrode potential, or a gas nozzle design (such asnozzle throat diameter, nozzle length, and/or nozzle divergent sectionhalf-angle) may be selected. Any one or more of the aforementioned GCIBproperties can be selected to achieve control of target etch processmetrics, such as those noted above. Furthermore, any one or more of theaforementioned GCIB properties can be modified to achieve control oftarget etch process metrics, such as those noted above.

In FIG. 3A, a schematic graphical illustration of a beam energydistribution function for a GCIB is illustrated. For example, FIG. 3Agraphically illustrates several beam energy distributions (30A, 30B,30C, 30D), wherein the peak beam energy decreases and the energydistribution broadens as one proceeds through the distributions indirection 35.

The beam energy distribution function for the GCIB may be modified bydirecting the respective GCIB along a GCIB path through an increasedpressure region such that at least a portion of the GCIB traverses theincreased pressure region. The extent of modification to the beam energydistribution may be characterized by a pressure-distance (d) integralalong the at least a portion of the GCIB path. When the value of thepressure-distance integral is increased (either by increasing thepressure and/or the path length (d)), the beam energy distribution isbroadened and the peak energy is decreased. When the value of thepressure-distance integral is decreased (either by decreasing thepressure and/or the path length (d)), the beam energy distribution isnarrowed and the peak energy is increased. As an example, one maybroaden the beam energy distribution to increase the beam divergence, orone may narrow the beam energy distribution to decrease the beamdivergence.

The pressure-distance integral along the at least a portion of the GCIBpath may be equal to or greater than about 0.0001 torr-cm.Alternatively, the pressure-distance integral along the at least aportion of the GCIB path may be equal to or greater than about 0.001torr-cm. Alternatively yet, the pressure-distance integral along the atleast a portion of the GCIB path may be equal to or greater than about0.01 torr-cm. As an example, the pressure-distance integral along the atleast a portion of the GCIB path may range from 0.0001 torr-cm to 0.01torr-cm. As another example, the pressure-distance integral along the atleast a portion of the GCIB path may range from 0.001 torr-cm to 0.01torr-cm.

Alternatively, the beam energy distribution function for the GCIB may bemodified by modifying or altering a charge state of the respective GCIB.For example, the charge state may be modified by adjusting an electronflux, an electron energy, or an electron energy distribution forelectrons utilized in electron collision-induced ionization of gasclusters.

In FIG. 3B, a schematic graphical illustration of a beam angulardistribution function for a GCIB is illustrated. For example, FIG. 3Bgraphically illustrates a first beam angular distribution function 40characterized by a first peak 42 at a direction of incidence 45 (i.e.,relative angle is 0°) and a first width 44 (e.g., a full-width at halfmaximum (FWHM)). Additionally, for example, FIG. 3B illustrates a secondbeam angular distribution function 40′ characterized by a second peak42′ at the direction of incidence 45 (i.e., relative angle is 0°) and asecond width 44′ (e.g., a full-width at half maximum (FWHM)). The firstbeam angular distribution function 40 represents a narrow distribution(or a relatively narrower beam divergence angle), while the second beamangular distribution function 40′ represents a relatively broaderdistribution (or a relatively broader beam divergence angle). Hence, thedirectionality of the GCIB relative to normal incidence on the substratemay be adjusted by altering the beam angular distribution function(e.g., changing the angular distribution between the first beam angulardistribution function 40 and the second beam angular distributionfunction 40′). The beam angular distribution function or beam divergenceangle may be modified using the aforementioned techniques described formodifying the beam energy distribution function.

In one embodiment, the one or more GCIB properties of the GCIB processcondition may include a GCIB composition, a beam dose, a beamacceleration potential, a beam focus potential, a beam energy, a beamenergy distribution, a beam angular distribution, a beam divergenceangle, a flow rate of said GCIB composition, a stagnation pressure, astagnation temperature, a background gas pressure for an increasedpressure region through which said GCIB passes, or a background gas flowrate for an increased pressure region through which said GCIB passes(e.g., a pressure cell (P-Cell) value, as will be discussed in greaterdetail below).

In another embodiment, the setting of the one or more GCIB properties toachieve the one or more target etch process metrics may include settinga GCIB composition, a beam acceleration potential, a flow rate of theGCIB composition, and a background gas flow rate for an increasedpressure region through which the GCIB passes to achieve two or more ofa target etch rate for the first material and/or the second material, atarget etch selectivity between the first material and the secondmaterial, and a target surface roughness for the first material and/orthe second material.

As will be shown below, the one or more GCIB properties may be adjustedto alter the target etch selectivity between the first and secondmaterials to values less than unity, substantially near unity, and aboveunity. Furthermore, as will be shown below, the one or more GCIBproperties may be adjusted to alter the target surface roughness for thefirst material and/or the second material to values less than or equalto 5 Angstrom. Further yet, the one or more GCIB properties may beadjusted to achieve a relatively high etch rate condition for the firstand/or second materials, or achieve a relatively low etch rate conditionfor the first and/or second materials.

When using the pressure cell, the GCIB may be accelerated through thereduced pressure environment towards the substrate according to a beamacceleration potential. For the GCIB, the beam acceleration potentialmay range up to 100 kV, the beam energy may range up to 100 keV, thecluster size may range up to several tens of thousands of atoms, and thebeam dose may range up to about 1×10¹⁷ clusters per cm². For example,the beam acceleration potential of the GCIB may range from about 1 kV toabout 70 kV (i.e., the beam energy may range from about 1 keV to about70 keV, assuming an average cluster charge state of unity).Additionally, for example, the beam dose of the GCIB may range fromabout 1×10¹² clusters per cm² to about 1×10¹⁴ clusters per cm².

The GCIB may be established having an energy per atom ratio ranging fromabout 0.25 eV per atom to about 100 eV per atom. Alternatively, the GCIBmay be established having an energy per atom ratio ranging from about0.25 eV per atom to about 10 eV per atom. Alternatively, the GCIB may beestablished having an energy per atom ratio ranging from about 1 eV peratom to about 10 eV per atom.

The establishment of the GCIB having a desired energy per atom ratio mayinclude selection of a beam acceleration potential, a stagnationpressure for formation of the GCIB, or a gas flow rate, or anycombination thereof. The beam acceleration potential may be used toincrease or decrease the beam energy or energy per ion cluster. Forexample, an increase in the beam acceleration potential causes anincrease in the maximum beam energy and, consequently, an increase inthe energy per atom ratio for a given cluster size. Additionally, thestagnation pressure may be used to increase or decrease the cluster sizefor a given cluster. For example, an increase in the stagnation pressureduring formation of the GCIB causes an increase in the cluster size(i.e., number of atoms per cluster) and, consequently, a decrease in theenergy per atom ratio for a given beam acceleration potential.

Herein, beam dose is given the units of number of clusters per unitarea. However, beam dose may also include beam current and/or time(e.g., GCIB dwell time). For example, the beam current may be measuredand maintained constant, while time is varied to change the beam dose.Alternatively, for example, the rate at which clusters strike thesurface of the substrate per unit area (i.e., number of clusters perunit area per unit time) may be held constant while the time is variedto change the beam dose.

The GCIB is irradiated onto at least a portion of the surface of thesubstrate with or without using a mask layer to etch at least part ofthe second layer 13A on the substrate 11 to form the contact via 15C.

The method described in FIG. 2 may further include altering the one ormore target etch process metrics to create one or more new target etchprocess metrics, and setting one or more additional GCIB properties ofan additional GCIB process condition for the GCIB to achieve the one ormore new target etch process metrics.

According to another embodiment, in addition to irradiation of thesubstrate 11 with the GCIB, another GCIB may be used for additionalcontrol and/or function. Irradiation of the substrate 11 by anotherGCIB, such as a second GCIB, may proceed before, during, or after use ofthe GCIB. For example, another GCIB may be used to dope a portion of thesubstrate 11 with an impurity. Additionally, for example, another GCIBmay be used to modify a portion of the substrate 11 to alter propertiesof substrate 11. Additionally, for example, another GCIB may be used toetch a portion of the substrate 11 to remove additional material fromsubstrate 11. Additionally, for example, another GCIB may be used toclean a portion of the substrate 11 to remove additional material orresidue, such as halogen-containing residue, from substrate 11.Additionally yet, for example, another GCIB may be used to grow ordeposit material on a portion of the substrate 11. The doping,modifying, etching, cleaning, growing, or depositing may compriseintroducing one or more elements selected from the group consisting ofHe, Ne, Ar, Xe, Kr, B, C, Se, Te, Si, Ge, N, P, As, O, S, F, Cl, and Br.

According to another embodiment, at least one portion of substrate 11subjected to GCIB irradiation may be cleaned before or after theirradiating with the GCIB. For example, the cleaning process may includea dry cleaning process and/or a wet cleaning process. Additionally, theat least one portion of substrate 11 subjected to GCIB irradiation maybe annealed after the irradiating with the GCIB.

According to another embodiment, when preparing and/or etching substrate11, any portion of substrate 11, or the contact via/contact via pattern,may be subjected to corrective processing. During corrective processing,metrology data may be acquired using a metrology system coupled to aGCIB processing system, either in-situ or ex-situ. The metrology systemmay comprise any variety of substrate diagnostic systems including, butnot limited to, optical diagnostic systems, X-ray fluorescencespectroscopy systems, four-point probing systems, transmission-electronmicroscope (TEM), atomic force microscope (AFM), scanning-electronmicroscope (SEM), etc. Additionally, the metrology system may comprisean optical digital profilometer (ODP), a scatterometer, an ellipsometer,a reflectometer, an interferometer, or any combination of two or morethereof.

For example, the metrology system may constitute an opticalscatterometry system. The scatterometry system may include ascatterometer, incorporating beam profile ellipsometry (ellipsometer)and beam profile reflectometry (reflectometer), commercially availablefrom KLA-Tencor Corporation, (One Technology Drive, Milpitas, Calif.95035), or Nanometrics, Inc. (1550 Buckeye Drive, Milpitas, Calif.95035). Additionally, for example, the in-situ metrology system mayinclude an integrated Optical Digital Profilometry (iODP) scatterometrymodule configured to measure metrology data on a substrate.

The metrology data may include parametric data, such as geometrical,mechanical, electrical and/or optical parameters associated with thesubstrate, any layer or sub-layer formed on the substrate, and/or anyportion of a device on the substrate. For example, metrology data caninclude any parameter measurable by the metrology systems describedabove. Additionally, for example, metrology data can include a filmthickness, a surface and/or interfacial roughness, a surfacecontamination, a feature depth, a trench depth, a via depth, a featurewidth, a trench width, a via width, a critical dimension (CD), anelectrical resistance, or any combination of two or more thereof.

The metrology data may be measured at two or more locations on thesubstrate. Moreover, this data may be acquired and collected for one ormore substrates. The one or more substrates may, for instance, include acassette of substrates. The metrology data is measured at two or morelocations on at least one of the one or more substrates and may, forexample, be acquired at a plurality of locations on each of the one ormore substrates. Thereafter, the plurality of locations on each of theplurality of substrates can be expanded from measured sites tounmeasured sites using a data fitting algorithm. For example, the datafitting algorithm can include interpolation (linear or nonlinear) orextrapolation (linear or nonlinear) or a combination thereof.

Once metrology data is collected for the one or more substrates usingthe metrology system, the metrology data is provided to a controller forcomputing correction data. Metrology data may be communicated betweenthe metrology system and the controller via a physical connection (e.g.,a cable), or a wireless connection, or a combination thereof.Additionally, the metrology data may be communicated via an intranet orInternet connection. Alternatively, metrology data may be communicatedbetween the metrology system and the controller via a computer readablemedium.

Correction data may be computed for location specific processing of thesubstrate. The correction data for a given substrate comprises a processcondition for modulation of the GCIB dose as a function of position onthe substrate in order to achieve a change between the parametric dataassociated with the incoming metrology data and the target parametricdata for the given substrate. For example, the correction data for agiven substrate can comprise determining a process condition for usingthe GCIB to correct a non-uniformity of the parametric data for thegiven substrate. Alternatively, for example, the correction data for agiven substrate can comprise determining a process condition for usingthe GCIB to create a specifically intended non-uniformity of theparametric data for the given substrate.

Using an established relationship between the desired change inparametric data and the GCIB dose and an established relationshipbetween the GCIB dose and a GCIB process condition having a set of GCIBprocessing parameters, the controller determines correction data foreach substrate. For example, a mathematical algorithm can be employed totake the parametric data associated with the incoming metrology data,compute a difference between the incoming parametric data and the targetparametric data, invert the GCIB processing pattern (i.e., etchingpattern or deposition pattern or both) to fit this difference, andcreate a beam dose contour to achieve the GCIB processing pattern usingthe relationship between the change in parametric data and the GCIBdose. Thereafter, for example, GCIB processing parameters can bedetermined to affect the calculated beam dose contour using therelationship between the beam dose and the GCIB process condition. TheGCIB processing parameters can include a beam dose, a beam area, a beamprofile, a beam intensity, a beam scanning rate, or an exposure time (orbeam dwell time), or any combination of two or more thereof.

Many different approaches to the selection of mathematical algorithm maybe successfully employed in this embodiment. In another embodiment, thebeam dose contour may selectively deposit additional material in orderto achieve the desired change in parametric data.

The correction data may be applied to the substrate using a GCIB. Duringcorrective processing, the GCIB may be configured to perform at leastone of smoothing, amorphizing, modifying, doping, etching, growing, ordepositing, or any combination of two or more thereof. The applicationof the corrective data to the substrate may facilitate correction ofsubstrate defects, correction of substrate surface planarity, correctionof layer thickness, or improvement of layer adhesion. Once processed toGCIB specifications, the uniformity of the substrate(s) or distributionof the parametric data for the substrate(s) may be examined eitherin-situ or ex-situ, and the process may be finished or refined asappropriate.

TABLE 1 GCIB Beam Process Acceleration Condition GCIB CompositionPotential (kV) P-Cell A Ar 30 0 B  5% NF₃/N₂ 30 0 C  5% NF₃/N₂ 60 0 D20% CHF₃/He 60 0 E 20% CHF₃/He + O₂ 60 0 F 10% C₂F₆/He 60 0 G 10%C₂HF₅/He 60 0 H 20% CF₄/He 60 0 I  4% Cl₂/He 30 0 J  4% Cl₂/He 60 40 K 4% Cl₂/He + O₂ 60 40 L  4% Cl₂/He + O₂ 60 0

Turning now to FIGS. 4A through 4L, exemplary data for etching materialon a substrate is graphically depicted. In particular, exemplary data isprovided for etching silicon oxide and silicon nitride relative to oneanother, as well as relative to silicon and/or other Si-containing orGe-containing layers or substrate materials. The data is useful inillustrating the dependence of several important GCIB etching processmetrics on GCIB parameters. And, the data is applicable to defining GCIBprocess conditions for contact via patterning.

FIG. 4A is a bar graph of a normalized etch rate of silicon dioxide(SiO₂) as a function of twelve (12) GCIB process conditions. The GCIBprocess conditions for the twelve (12) GCIB etch processes are providedin Table 1. The etch rate for each GCIB process condition is normalizedby the etch rate using an Ar GCIB, which is listed as GCIB processcondition “A” in Table 1.

In Table 1, each GCIB process condition provides a GCIB composition, abeam acceleration potential (kV), and a P-Cell value that relates tomodification of the beam energy distribution function. Concerning theGCIB composition, the notation “5% NF₃/N₂” represents the relativeamount (mol/mol %) of NF₃ in N₂. Concerning the P-Cell value, asdescribed above, the P-Cell value is related to a flow rate (in sccm,standard cubic centimeters per minute) of a background gas introduced toan increased pressure region to cause collisions between the GCIB andthe background gas and, thus, broadening of the beam energy distributionfunction. For example, the pressure in the pressure cell, through whichthe GCIB traverses, is raised by introducing a background gas at a flowrate of 40 sccm (P-Cell value of “40”) (or a pressure-distance integralof about 0.005 torr-cm) to the pressure cell (the relationship forP-Cell value is approximately linear with pressure).

As illustrated in FIG. 4A, the etch rate of silicon dioxide (SiO₂) wasdetermined for a wide range of GCIB process conditions. When the GCIBcontains only Ar, as in GCIB process condition “A”, the etch rate isdriven by a purely physical component, e.g., sputtering. However, FIG.4A and Table 1 suggest that the GCIB composition may be selected toprovide a chemical component to the etch process, and an increase in theetch rate.

As shown in FIG. 4B, a bar graph charts the etch selectivity betweensilicon dioxide (SiO₂) and photo-resist as a function of the GCIBprocess conditions in Table 1. The etch selectivity relates the etchrate of silicon dioxide (SiO₂) to the etch rate of photo-resist (P.R.)(i.e., E/R SiO₂/ E/R P.R.). Inspection of FIG. 4B indicates that aCHF₃-based GCIB composition and a Cl₂-based GCIB composition provide anetch selectivity in excess of unity.

FIG. 4C is a data graph of etch rate of silicon dioxide (SiO₂) andphoto-resist (P.R.) as a function of GCIB process condition and P-Cellvalue. The GCIB process conditions for three (3) GCIB etch processes areprovided in Table 2. In Table 2, each GCIB process condition provides aGCIB composition, a beam acceleration potential (kV), and a flow rate(sccm) for each chemical component in the respective GCIB composition.As evident from FIG. 4C, the etch rate for both silicon dioxide andphoto-resist using any of the three GCIB process conditions decreases asthe P-Cell value is increased.

TABLE 2 O₂ Beam CHF₃/He Flow Acceleration Flow Rate Rate Cl₂/He FlowGCIB Composition Potential (kV) (sccm) (sccm) Rate (sccm) 20% CHF₃/He 60400 0 0 20% CHF₃/He + O₂ 60 100 300 0  4% Cl₂/He 60 0 0 550

As shown in FIG. 4D, a bar graph charts the etch selectivity betweensilicon dioxide (SiO₂) and photo-resist as a function of the GCIBprocess conditions in Table 2. The etch selectivity relates the etchrate of silicon dioxide (SiO₂) to the etch rate of photo-resist (P.R.)(i.e., E/R SiO₂/ E/R P.R.). Inspection of FIG. 4D indicates thefollowing: (1) Etch selectivity between SiO₂ and P.R. increases withincreasing P-Cell value; (2) Etch selectivity between SiO₂ and P.R. mayslightly increase with oxygen addition in a halomethane composition,particularly at higher P-Cell value; and (3) CHF₃-based GCIB compositionprovides high etch selectivity between SiO₂ and P.R. than Cl₂-based GCIBcomposition.

As shown in FIG. 4E, a data graph of the surface roughness of the etchsurface in silicon dioxide (SiO₂) is plotted as a function of the GCIBprocess condition in Table 2 and P-Cell value. The surface roughness(R_(a), measured in Angstrom, A) represents an average roughness. Thedegree of roughness may be a measure of the interfacial and/or surfaceunevenness. For example, the degree of roughness, such as surfaceroughness, may be characterized mathematically as a maximum roughness(R_(max)), an average roughness (R_(a)) (as shown in FIG. 4E), or aroot-mean-square (rms) roughness (R_(q)). Inspection of FIG. 4Eindicates the following: (1) Average roughness of SiO₂ surface decreaseswith increasing P-Cell value; and (2) CHF₃-based GCIB compositionprovides a slightly higher average roughness on SiO₂ than Cl₂-based GCIBcomposition.

As shown in FIG. 4F, a bar graph charts the etch rate of silicon dioxide(SiO₂) and the etch selectivity between silicon dioxide (SiO₂) andphoto-resist as a function of the GCIB process conditions in Table 3.The etch selectivity relates the etch rate of silicon dioxide (SiO₂) tothe etch rate of photo-resist (P.R.) (i.e., E/R SiO₂/E/R P.R.). The GCIBcompositions for the three (3) GCIB process conditions in Table 3 arethe same as in Table 2; however, some GCIB process conditions areadjusted to achieve relatively low surface roughness (of order magnitudeof 3 Angstrom or less).

TABLE 3 Beam CHF₃/He O₂ Etch Average Acceleration P-Cell Flow Rate FlowRate Cl₂/He Flow Selectivity Roughness GCIB Composition Potential (kV)Value (sccm) (sccm) Rate (sccm) (SiO₂/P.R.) (A) 20% CHF₃/He 60 40 300 00 3.3 3.0 20% CHF₃/He + O₂ 60 40 75 225 0 3.0 3.6  4% Cl₂/He 60 40 0 0550 0.8 3.3

Table 3 provides the beam acceleration potential, the P-Cell value, theflow rates of each pressurized gas in the GCIB composition, and theresultant etch selectivity and average roughness. FIG. 4F displays thecorresponding relative etch rate and etch selectivity. Clearly, theCHF₃-based GCIB composition achieves relatively low surface roughnesswith relatively high etch selectivity.

FIG. 4G is a bar graph of the etch selectivity for photo-resist (P.R.),silicon dioxide (SiO₂), and silicon nitride (SiN) relative topoly-crystalline silicon (Si) as a function of flow rate for a GCIBcomposition of 20% CHF₃/He. The GCIB process condition further includesa beam acceleration potential of 60 kV and a P-Cell value of 0. As theflow rate is increased from 350 sccm to 550 sccm, the etch selectivityfor P.R., SiO₂, and SiN relative to Si decays from a value above unityto a value below unity.

FIG. 4H is a bar graph of the etch selectivity between silicon dioxide(SiO₂) and poly-crystalline silicon (Si) as a function of GCIB processcondition for a GCIB composition of 10% CHF₃/He. As shown in FIG. 4H, anincrease in P-Cell value increases the etch selectivity between SiO₂ andSi, while an increase in flow rate decreases the etch selectivitybetween SiO₂ and Si.

TABLE 4 Beam CHF₃/He CHF₃/O₂ O₂ He CHClF₂/He Etch Average AccelerationP-Cell Flow Rate Flow Rate Flow Rate Flow Rate Flow Rate SelectivityRoughness GCIB Composition Potential (kV) Value (sccm) (sccm) (sccm)(sccm) (sccm) (SiO₂/Si) (A) 20% CHF₃/He 60 40 350 0 0 0 0 6.4 2.5 20%CHF₃/He + O₂ 60 40 125 0 125 0 0 7.2 2.2  4% CHClF₂/He 60 40 0 0 0 0 6809.1 4.0 10% CHF₃/O₂ 60 50 0 200 0 0 0 7.9 1.3 10% CHF₃/O₂ 60 40 0 230 00 0 6.6 2.7 10% CHF₃/O₂ + He 60 40 0 180 0 125 0 12.2 1.1 10% CHF₃/O₂ 3040 0 300 0 0 0 3.7 8.4 20% CHF₃/He 30 40 475 0 0 0 0 1.1 3.9

In Table 4, several GCIB process conditions, and the resultant etchselectivity (between SiO₂ and Si) and average roughness are provided.The etch selectivity may be varied from a value of about 1 to about 12,while achieving an average roughness ranging from about 1A to about 4A,by adjusting various GCIB process conditions, including GCIBcomposition, beam acceleration potential, P-Cell value, and flow rate.

FIG. 4I is a data graph of the etch rate of SiO₂, the etch rate ofpoly-crystalline silicon (Si), and the etch selectivity between SiO₂ andSi as a function of the flow rate of He added to a GCIB composition of10% CHF₃/O₂. The GCIB process condition for the peak value of etchselectivity (about 12.2) is provided in Table 4 (see row 6). Whilevarying the He flow rate, the remaining parameters in the GCIB processcondition were held constant.

FIG. 4J is a bar graph of the etch selectivity for photo-resist (P.R.),silicon dioxide (SiO₂), and silicon nitride (SiN) relative topoly-crystalline silicon (Si) as a function of P-Cell value for a GCIBcomposition of 10% CClF₃/He. The GCIB process condition further includesa beam acceleration potential of 60 kV and a flow rate of 450 sccm. Asthe P-Cell value is increased from 0 to 40, the etch selectivity forSiO₂ and SiN relative to Si increases, while the etch selectivity forP.R. relative to Si decreases.

TABLE 5 Beam CBrF₃/He Etch Average Acceleration P-Cell Flow Rate N₂ FlowSelectivity Roughness- GCIB Composition Potential (kV) Value (sccm) Rate(sccm) (Si/SiO₂) Si (A) 10% CBrF₃/He 30 40 400 2.5 22.0 10% CBrF₃/He 300 351 2.3 19.1 10% CBrF₃/He 45 40 400 1.8 27.0 10% CBrF₃/He 60 40 4001.4 28.0 10% CBrF₃/He 30 40 351 1.3 13.8 10% CBrF₃/He 30 40 350 0.9 18.010% CBrF₃/He 30 40 400 0.7 16.0 10% CBrF₃/He 60 20 350 0.6 8.7 10%CBrF₃/He 60 40 350 0.5 6.7 10% CBrF₃/He 60 40 151 350 0.5 6.7 10%CBrF₃/He 60 20 151 150 0.5 5.0 10% CBrF₃/He 60 40 175 175 0.5 3.7 10%CBrF₃/He 45 40 151 150 0.4 4.6 10% CBrF₃/He 60 40 151 250 0.4 4.6 10%CBrF₃/He 60 40 400 0.4 3.8 10% CBrF₃/He 60 40 150 150 0.4 3 10% CBrF₃/He60 40 350 0.3

FIG. 4K is a bar graph of the etch selectivity for photo-resist (P.R.),silicon dioxide (SiO₂), and silicon nitride (SiN) relative topoly-crystalline silicon (Si) as a function of beam accelerationpotential for a GCIB composition of 10% CClF₃/He. The GCIB processcondition further includes a P-Cell value of 0 and a flow rate of 450sccm. As the beam acceleration potential is decreased from 60 kV to 10kV, the etch selectivity for P.R., SiO₂, and SiN relative to Sidecreases.

In Table 5, several GCIB process conditions, and the resultant etchselectivity (between Si and SiO₂) and average roughness in Si areprovided. Each GCIB process condition recites a GCIB compositioncontaining 10% CBrF₃ in He. In some cases, N₂ is added to the GCIB. Theetch selectivity may be varied from a value of about 0.3 to about 2.5,while achieving an average roughness ranging from about 3A to about 30A,by adjusting various GCIB process conditions, including GCIBcomposition, beam acceleration potential, P-Cell value, and flow rate.For example, N₂ addition coupled with increased beam accelerationpotential, increased P-Cell value, and decreased flow rate of the etchcompound produces the least average roughness.

TABLE 6 Beam CF₄/He Additive Etch Average Acceleration P-Cell Flow RateFlow Rate Selectivity Roughness- GCIB Composition Potential (kV) Value(sccm) (sccm) (Si/SiO₂) Si (A) 20% CF₄/He 30 0 451 0.54 14.1 20% CF₄/He60 40 550 0.48 5.1 20% CF₄/He 60 0 451 0.47 18.6 20% CF₄/He 60 40 4510.32 2.4

TABLE 7 Beam NF₃/N₂ Etch Etch Average Acceleration P-Cell Flow RateSelectivity Selectivity Roughness- GCIB Composition Potential (kV) Value(sccm) (Si/SiN) (p-Si/SiN) Si (A) 20% NF₃/N₂ 30 10 500 3.8 31 20% NF₃/N₂30 40 500 3.8 20 20% NF₃/N₂ 60 10 750 3.5 60 20% NF₃/N₂ 30 50 450 3.23.4 16 20% NF₃/N₂ 60 10 500 2.7 33 20% NF₃/N₂ 60 10 500 2.4 35 20%NF₃/N₂ 45 10 400 2.3 2.3 30 20% NF₃/N₂ 45 10 350 1.8 1.9 22 20% NF₃/N₂45 50 450 1.7 1.8 15 20% NF₃/N₂ 45 30 350 1.5 1.6 15 20% NF₃/N₂ 30 40350 1.5 11 20% NF₃/N₂ 45 30 400 1.4 1.5 17 20% NF₃/N₂ 60 10 500 1.4 2620% NF₃/N₂ 60 50 500 1.3 17 20% NF₃/N₂ 60 10 500 1.3 24 20% NF₃/N₂ 45 40350 1.2 10 20% NF₃/N₂ 45 50 350 1.2 1.3 8 20% NF₃/N₂ 45 50 400 1.1 1.410 20% NF₃/N₂ 60 10 250 1.1 11 20% NF₃/N₂ 60 40 250 0.9 2 20% NF₃/N₂ 6040 250 0.9 3

In Table 6, several GCIB process conditions, and the resultant etchselectivity (between Si and SiO₂) and average roughness in Si areprovided. Each GCIB process condition recites a GCIB compositioncontaining 20% CF₄ in He. The etch selectivity may be varied from avalue of about 0.32 to about 0.54, while achieving an average roughnessranging from about 2A to about 19A, by adjusting various GCIB processconditions, including GCIB composition, beam acceleration potential,P-Cell value, and flow rate.

TABLE 8 Beam Cl₂/N₂ Additive Etch Average Acceleration P-Cell Flow RateFlow Rate Selectivity Roughness- GCIB Composition Potential (kV) Value(sccm) (sccm) (Si/SiN) Si (A) 6% Cl₂/N₂ 10 0 350 8.2 92 6% Cl₂/N₂ 30 0350 3.3 46 6% Cl₂/N₂ 10 0 425 8.7 6% Cl₂/N₂ 30 0 425 3.7 6% Cl₂/N₂ 10 0500 10.7 6% Cl₂/N₂ 30 0 500 4.9 6% Cl₂/N₂ 60 40 350 3.3 32.5 6% Cl₂/N₂60 40 350 3.7 44 6% Cl₂/N₂ 60 25 350 3.3 6% Cl₂/N₂ 60 50 350 3.5 47.8 6%Cl₂/N₂ 60 50 450 5 69 6% Cl₂/N₂ 60 50 550 4.6 105 4% Cl₂/N₂ 60 50 225125 (N₂) 2.7 16.6 6% Cl₂/N₂ 60 50 300  50 (He) 3.2 31 6% Cl₂/N₂ 30 50350 5.3 83 2% Cl₂/N₂ 60 50 125 225 (N₂) 0.7 11.6 4% Cl₂/N₂ 60 50 225 125(Ar) 3.5 34

In Table 7, several GCIB process conditions, and the resultant etchselectivity (between Si and SiN) and average roughness in Si areprovided. Each GCIB process condition recites a GCIB compositioncontaining 20% NF₃ in N₂. The etch selectivity may be varied from avalue of about 1 to about 4, while achieving an average roughnessranging from about 2A to about 60A, by adjusting various GCIB processconditions, including GCIB composition, beam acceleration potential,P-Cell value, and flow rate. A high etch rate and etch selectivity maybe achieved at the expense of average roughness. Furthermore, the etchselectivity between Si and SiN appears to be similar to the etchselectivity between p-doped Si and SiN.

In Table 8, several GCIB process conditions, and the resultant etchselectivity (between Si and SiN) and average roughness in Si areprovided. Each GCIB process condition recites a GCIB compositioncontaining 2%-6% Cl₂ in N₂. In some cases, He, Ar, or N₂ are added tothe GCIB. The etch selectivity may be varied from less than unity toabout 11, while achieving an average roughness ranging from about 12 Ato about 105 A, by adjusting various GCIB process conditions, includingGCIB composition, beam acceleration potential, P-Cell value, and flowrate.

In Table 9, several GCIB process conditions, and the resultant etchselectivity (between Si and SiN) and average roughness in Si areprovided. Each GCIB process condition recites a GCIB compositioncontaining 4%-6% Cl₂ in He. The etch selectivity may be varied from avalue of about 1.4 to about 6, while achieving an average roughnessranging from about 5 A to about 40 A, by adjusting various GCIB processconditions, including GCIB composition, beam acceleration potential,P-Cell value, and flow rate. The use of He as a carrier for Cl₂ appearsto produce lower average roughness than the use of N₂ as a carrier forCl₂.

TABLE 9 Beam Cl₂/He Additive Etch Average Acceleration P-Cell Flow RateFlow Rate Selectivity Roughness- GCIB Composition Potential (kV) Value(sccm) (sccm) (Si/SiN) Si (A) 6% Cl₂/He 10 0 500 6.1 6% Cl₂/He 10 0 5506.8 6% Cl₂/He 30 0 500 2.8 38.4 6% Cl₂/He 30 0 550 3.4 30.0 4% Cl₂/He 600 575 2 13.0 4% Cl₂/He 60 20 575 1.9 13.0 4% Cl₂/He 60 40 575 2.1 7.1 4%Cl₂/He 30 0 575 1.6 4% Cl₂/He 30 40 600 1.4 4.6

In Table 10, several GCIB process conditions, and the resultant etchselectivity (between Si and SiN) and average roughness in Si areprovided. Each GCIB process condition recites a GCIB compositioncontaining 35% HCl in He. The etch selectivity may be varied from avalue of about 2 to about 7, while achieving an average roughnessranging from about 15 A to about 25 A, by adjusting various GCIB processconditions, including GCIB composition, beam acceleration potential,P-Cell value, and flow rate.

TABLE 10 Beam HCl/He Additive Etch Average Acceleration P-Cell Flow RateFlow Rate Selectivity Roughness- GCIB Composition Potential (kV) Value(sccm) (sccm) (Si/SiN) Si (A) 35% HCl/He 10 0 400 4.9 16.0 35% HCl/He 100 400 4.9 15.0 35% HCl/He 30 0 400 2.0 20.0 35% HCl/He 30 0 400 35%HCl/He 60 40 400 2.6 23.0 35% HCl/He 10 0 475 6.9 18.0 35% HCl/He 10 0475 6.6 18.0 35% HCl/He 30 0 475 2.8 25.0 35% HCl/He 30 0 475 2.2 23.0

In FIG. 4L, exemplary data for etching material on a substrate isgraphically depicted. FIG. 4L is a bar graph of etch rate of severalmaterials, including NiFe, Cu, CoFe, Al, Al₂O₃, Ru, W, Mo, TaN, Ta, AlN,SiO₂, SiN, Si, SiC, photo-resist (P.R.), and SiCOH, for three (3) GCIBetch processes. The GCIB processes include: (A) Ar; (B) 5% NF₃/N₂; and(C) 4% Cl₂/He. The GCIB process conditions for the three (3) GCIB etchprocesses are provided in Table 11.

TABLE 11 GCIB Beam Process Acceleration Flow Rate Condition GCIBComposition Potential (kV) p-Cell (sccm) A Ar 30 0 250 B 5% NF₃/N₂ 30 0500 C 4% Cl₂/He 30 0 700

In Table 11, each GCIB process condition provides a GCIB composition, abeam acceleration potential (kV), a P-Cell value that relates tomodification of the beam energy distribution function, and a flow rateof the GCIB composition.

As illustrated in FIG. 4L, the etch rate of several metal-containingmaterials, such as CoFe, NiFe, and Al, tends to improve when using aCl-based GCIB chemistry, as opposed to a F-based GCIB chemistry. Also,when the GCIB contains only Ar, as in GCIB process condition “A”, theetch rate is driven by a purely physical component, e.g., sputtering.However, FIG. 4L and Table 11 suggest that the GCIB composition may beselected to provide a chemical component to the etch process, and anincrease in the etch rate.

According to another example, when etching an ONO layer to pattern a HARcontact via, the etching gas may include CHF₃. The etching gas mayfurther include an oxygen-containing gas, such as O₂. As noted above, aCHF₃-based GCIB etching process can achieve the target etch processmetrics noted above. The P-Cell value has been determined by theinventors to reduce corner rounding. For example, the P-Cell value mayrange from 15 to 80, or more preferably 20 to 70, or even morepreferably 50 to 70 (e.g., a value of 60).

Referring now to FIG. 5, a GCIB processing system 100 for treating asubstrate as described above is depicted according to an embodiment. TheGCIB processing system 100 comprises a vacuum vessel 102, substrateholder 150, upon which a substrate 152 to be processed is affixed, andvacuum pumping systems 170A, 170B, and 170C. Substrate 152 can be asemiconductor substrate, a wafer, a flat panel display (FPD), a liquidcrystal display (LCD), or any other workpiece. GCIB processing system100 is configured to produce a GCIB for treating substrate 152.

Referring still to GCIB processing system 100 in FIG. 5, the vacuumvessel 102 comprises three communicating chambers, namely, a sourcechamber 104, an ionization/acceleration chamber 106, and a processingchamber 108 to provide a reduced-pressure enclosure. The three chambersare evacuated to suitable operating pressures by vacuum pumping systems170A, 170B, and 170C, respectively. In the three communicating chambers104, 106, 108, a gas cluster beam can be formed in the first chamber(source chamber 104), while a GCIB can be formed in the second chamber(ionization/acceleration chamber 106) wherein the gas cluster beam isionized and accelerated. Then, in the third chamber (processing chamber108), the accelerated GCIB may be utilized to treat substrate 152.

As shown in FIG. 5, GCIB processing system 100 can comprise one or moregas sources configured to introduce one or more gases or mixture ofgases to vacuum vessel 102. For example, a first gas composition storedin a first gas source 111 is admitted under pressure through a first gascontrol valve 113A to a gas metering valve or valves 113. Additionally,for example, a second gas composition stored in a second gas source 112is admitted under pressure through a second gas control valve 113B tothe gas metering valve or valves 113. Further, for example, the firstgas composition or second gas composition or both can include acondensable inert gas, carrier gas or dilution gas. For example, theinert gas, carrier gas or dilution gas can include a noble gas, i.e.,He, Ne, Ar, Kr, Xe, or Rn.

Furthermore, the first gas source 111 and the second gas source 112 maybe utilized either alone or in combination with one another to produceionized clusters. The material composition can include the principalatomic or molecular species of the elements desired to react with or beintroduced to the material layer.

The high pressure, condensable gas comprising the first gas compositionor the second gas composition or both is introduced through gas feedtube 114 into stagnation chamber 116 and is ejected into thesubstantially lower pressure vacuum through a properly shaped nozzle110. As a result of the expansion of the high pressure, condensable gasfrom the stagnation chamber 116 to the lower pressure region of thesource chamber 104, the gas velocity accelerates to supersonic speedsand gas cluster beam 118 emanates from nozzle 110.

The inherent cooling of the jet as static enthalpy is exchanged forkinetic energy, which results from the expansion in the jet, causes aportion of the gas jet to condense and form a gas cluster beam 118having clusters, each consisting of from several to several thousandweakly bound atoms or molecules. A gas skimmer 120, positioneddownstream from the exit of the nozzle 110 between the source chamber104 and ionization/acceleration chamber 106, partially separates the gasmolecules on the peripheral edge of the gas cluster beam 118, that maynot have condensed into a cluster, from the gas molecules in the core ofthe gas cluster beam 118, that may have formed clusters. Among otherreasons, this selection of a portion of gas cluster beam 118 can lead toa reduction in the pressure in the downstream regions where higherpressures may be detrimental (e.g., ionizer 122, and processing chamber108). Furthermore, gas skimmer 120 defines an initial dimension for thegas cluster beam entering the ionization/acceleration chamber 106.

The GCIB processing system 100 may also include multiple nozzles withone or more skimmer openings. Additional details concerning the designof a multiple gas cluster ion beam system are provided in U.S. PatentApplication Publication No. 2010/0193701A1, entitled “Multiple NozzleGas Cluster Ion Beam System” and filed on Apr. 23, 2009; and U.S. PatentApplication Publication No. 2010/0193472A1, entitled “Multiple NozzleGas Cluster Ion Beam Processing System and Method of Operating” andfiled on Mar. 26, 2010; the contents of which are herein incorporated byreference in their entirety.

After the gas cluster beam 118 has been formed in the source chamber104, the constituent gas clusters in gas cluster beam 118 are ionized byionizer 122 to form GCIB 128. The ionizer 122 may include an electronimpact ionizer that produces electrons from one or more filaments 124,which are accelerated and directed to collide with the gas clusters inthe gas cluster beam 118 inside the ionization/acceleration chamber 106.Upon collisional impact with the gas cluster, electrons of sufficientenergy eject electrons from molecules in the gas clusters to generateionized molecules. The ionization of gas clusters can lead to apopulation of charged gas cluster ions, generally having a net positivecharge.

As shown in FIG. 5, beam electronics 130 are utilized to ionize,extract, accelerate, and focus the GCIB 128. The beam electronics 130include a filament power supply 136 that provides voltage V_(F) to heatthe ionizer filament 124.

Additionally, the beam electronics 130 include a set of suitably biasedhigh voltage electrodes 126 in the ionization/acceleration chamber 106that extracts the cluster ions from the ionizer 122. The high voltageelectrodes 126 then accelerate the extracted cluster ions to a desiredenergy and focus them to define GCIB 128. The kinetic energy of thecluster ions in GCIB 128 typically ranges from about 1000 electron volts(1 keV) to several tens of keV. For example, GCIB 128 can be acceleratedto 1 to 100 keV.

As illustrated in FIG. 5, the beam electronics 130 further include ananode power supply 134 that provides voltage V_(A) to an anode ofionizer 122 for accelerating electrons emitted from ionizer filament 124and causing the electrons to bombard the gas clusters in gas clusterbeam 118, which produces cluster ions.

Additionally, as illustrated in FIG. 5, the beam electronics 130 includean extraction power supply 138 that provides voltage V_(EE) to bias atleast one of the high voltage electrodes 126 to extract ions from theionizing region of ionizer 122 and to form the GCIB 128. For example,extraction power supply 138 provides a voltage to a first electrode ofthe high voltage electrodes 126 that is less than or equal to the anodevoltage of ionizer 122.

Furthermore, the beam electronics 130 can include an accelerator powersupply 140 that provides voltage V_(ACC) to bias one of the high voltageelectrodes 126 with respect to the ionizer 122 so as to result in atotal GCIB acceleration energy equal to about V_(ACC) electron volts(eV). For example, accelerator power supply 140 provides a voltage to asecond electrode of the high voltage electrodes 126 that is less than orequal to the anode voltage of ionizer 122 and the extraction voltage ofthe first electrode.

Further yet, the beam electronics 130 can include lens power supplies142, 144 that may be provided to bias some of the high voltageelectrodes 126 with potentials (e.g., V_(L1) and V_(L2)) to focus theGCIB 128. For example, lens power supply 142 can provide a voltage to athird electrode of the high voltage electrodes 126 that is less than orequal to the anode voltage of ionizer 122, the extraction voltage of thefirst electrode, and the accelerator voltage of the second electrode,and lens power supply 144 can provide a voltage to a fourth electrode ofthe high voltage electrodes 126 that is less than or equal to the anodevoltage of ionizer 122, the extraction voltage of the first electrode,the accelerator voltage of the second electrode, and the first lensvoltage of the third electrode.

Note that many variants on both the ionization and extraction schemesmay be used. While the scheme described here is useful for purposes ofinstruction, another extraction scheme involves placing the ionizer andthe first element of the extraction electrode(s) (or extraction optics)at V_(ACC). This typically requires fiber optic programming of controlvoltages for the ionizer power supply, but creates a simpler overalloptics train. The invention described herein is useful regardless of thedetails of the ionizer and extraction lens biasing.

A beam filter 146 in the ionization/acceleration chamber 106 downstreamof the high voltage electrodes 126 can be utilized to eliminatemonomers, or monomers and light cluster ions from the GCIB 128 to definea filtered process GCIB 128A that enters the processing chamber 108. Inone embodiment, the beam filter 146 substantially reduces the number ofclusters having 100 or less atoms or molecules or both. The beam filtermay comprise a magnet assembly for imposing a magnetic field across theGCIB 128 to aid in the filtering process.

Referring still to FIG. 5, a beam gate 148 is disposed in the path ofGCIB 128 in the ionization/acceleration chamber 106. Beam gate 148 hasan open state in which the GCIB 128 is permitted to pass from theionization/acceleration chamber 106 to the processing chamber 108 todefine process GCIB 128A, and a closed state in which the GCIB 128 isblocked from entering the processing chamber 108. A control cableconducts control signals from control system 190 to beam gate 148. Thecontrol signals controllably switch beam gate 148 between the open orclosed states.

A substrate 152, which may be a wafer or semiconductor wafer, a flatpanel display (FPD), a liquid crystal display (LCD), or other substrateto be processed by GCIB processing, is disposed in the path of theprocess GCIB 128A in the processing chamber 108. Because mostapplications contemplate the processing of large substrates withspatially uniform results, a scanning system may be desirable touniformly scan the process GCIB 128A across large areas to producespatially homogeneous results.

An X-scan actuator 160 provides linear motion of the substrate holder150 in the direction of X-scan motion (into and out of the plane of thepaper). A Y-scan actuator 162 provides linear motion of the substrateholder 150 in the direction of Y-scan motion 164, which is typicallyorthogonal to the X-scan motion. The combination of X-scanning andY-scanning motions translates the substrate 152, held by the substrateholder 150, in a raster-like scanning motion through process GCIB 128Ato cause a uniform (or otherwise programmed) irradiation of a surface ofthe substrate 152 by the process GCIB 128A for processing of thesubstrate 152.

The substrate holder 150 disposes the substrate 152 at an angle withrespect to the axis of the process GCIB 128A so that the process GCIB128A has an angle of beam incidence 166 with respect to a substrate 152surface. The angle of beam incidence 166 may be 90 degrees or some otherangle, but is typically 90 degrees or near 90 degrees. DuringY-scanning, the substrate 152 and the substrate holder 150 move from theshown position to the alternate position “A” indicated by thedesignators 152A and 150A, respectively. Notice that in moving betweenthe two positions, the substrate 152 is scanned through the process GCIB128A, and in both extreme positions, is moved completely out of the pathof the process GCIB 128A (over-scanned). Though not shown explicitly inFIG. 5, similar scanning and over-scan is performed in the (typically)orthogonal X-scan motion direction (in and out of the plane of thepaper).

A beam current sensor 180 may be disposed beyond the substrate holder150 in the path of the process GCIB 128A so as to intercept a sample ofthe process GCIB 128A when the substrate holder 150 is scanned out ofthe path of the process GCIB 128A. The beam current sensor 180 istypically a Faraday cup or the like, closed except for a beam-entryopening, and is typically affixed to the wall of the vacuum vessel 102with an electrically insulating mount 182.

As shown in FIG. 5, control system 190 connects to the X-scan actuator160 and the Y-scan actuator 162 through electrical cable and controlsthe X-scan actuator 160 and the Y-scan actuator 162 in order to placethe substrate 152 into or out of the process GCIB 128A and to scan thesubstrate 152 uniformly relative to the process GCIB 128A to achievedesired processing of the substrate 152 by the process GCIB 128A.Control system 190 receives the sampled beam current collected by thebeam current sensor 180 by way of an electrical cable and, thereby,monitors the GCIB and controls the GCIB dose received by the substrate152 by removing the substrate 152 from the process GCIB 128A when apredetermined dose has been delivered.

In the embodiment shown in FIG. 6, the GCIB processing system 100′ canbe similar to the embodiment of FIG. 5 and further comprise a X-Ypositioning table 253 operable to hold and move a substrate 252 in twoaxes, effectively scanning the substrate 252 relative to the processGCIB 128A. For example, the X-motion can include motion into and out ofthe plane of the paper, and the Y-motion can include motion alongdirection 264.

The process GCIB 128A impacts the substrate 252 at a projected impactregion 286 on a surface of the substrate 252, and at an angle of beamincidence 266 with respect to the surface of substrate 252. By X-Ymotion, the X-Y positioning table 253 can position each portion of asurface of the substrate 252 in the path of process GCIB 128A so thatevery region of the surface may be made to coincide with the projectedimpact region 286 for processing by the process GCIB 128A. An X-Ycontroller 262 provides electrical signals to the X-Y positioning table253 through an electrical cable for controlling the position andvelocity in each of X-axis and Y-axis directions. The X-Y controller 262receives control signals from, and is operable by, control system 190through an electrical cable. X-Y positioning table 253 moves bycontinuous motion or by stepwise motion according to conventional X-Ytable positioning technology to position different regions of thesubstrate 252 within the projected impact region 286. In one embodiment,X-Y positioning table 253 is programmably operable by the control system190 to scan, with programmable velocity, any portion of the substrate252 through the projected impact region 286 for GCIB processing by theprocess GCIB 128A.

The substrate holding surface 254 of positioning table 253 iselectrically conductive and is connected to a dosimetry processoroperated by control system 190. An electrically insulating layer 255 ofpositioning table 253 isolates the substrate 252 and substrate holdingsurface 254 from the base portion 260 of the positioning table 253.Electrical charge induced in the substrate 252 by the impinging processGCIB 128A is conducted through substrate 252 and substrate holdingsurface 254, and a signal is coupled through the positioning table 253to control system 190 for dosimetry measurement. Dosimetry measurementhas integrating means for integrating the GCIB current to determine aGCIB processing dose. Under certain circumstances, a target-neutralizingsource (not shown) of electrons, sometimes referred to as electronflood, may be used to neutralize the process GCIB 128A. In such case, aFaraday cup (not shown, but which may be similar to beam current sensor180 in FIG. 5) may be used to assure accurate dosimetry despite theadded source of electrical charge, the reason being that typical Faradaycups allow only the high energy positive ions to enter and be measured.

In operation, the control system 190 signals the opening of the beamgate 148 to irradiate the substrate 252 with the process GCIB 128A. Thecontrol system 190 monitors measurements of the GCIB current collectedby the substrate 252 in order to compute the accumulated dose receivedby the substrate 252. When the dose received by the substrate 252reaches a predetermined dose, the control system 190 closes the beamgate 148 and processing of the substrate 252 is complete. Based uponmeasurements of the GCIB dose received for a given area of the substrate252, the control system 190 can adjust the scan velocity in order toachieve an appropriate beam dwell time to treat different regions of thesubstrate 252.

Alternatively, the process GCIB 128A may be scanned at a constantvelocity in a fixed pattern across the surface of the substrate 252;however, the GCIB intensity is modulated (may be referred to as Z-axismodulation) to deliver an intentionally non-uniform dose to the sample.The GCIB intensity may be modulated in the GCIB processing system 100′by any of a variety of methods, including varying the gas flow from aGCIB source supply; modulating the ionizer 122 by either varying afilament voltage V_(F) or varying an anode voltage V_(A); modulating thelens focus by varying lens voltages V_(L1) and/or V_(L2); ormechanically blocking a portion of the GCIB with a variable beam block,adjustable shutter, or variable aperture. The modulating variations maybe continuous analog variations or may be time modulated switching orgating.

The processing chamber 108 may further include an in-situ metrologysystem. For example, the in-situ metrology system may include an opticaldiagnostic system having an optical transmitter 280 and optical receiver282 configured to illuminate substrate 252 with an incident opticalsignal 284 and to receive a scattered optical signal 288 from substrate252, respectively. The optical diagnostic system comprises opticalwindows to permit the passage of the incident optical signal 284 and thescattered optical signal 288 into and out of the processing chamber 108.Furthermore, the optical transmitter 280 and the optical receiver 282may comprise transmitting and receiving optics, respectively. Theoptical transmitter 280 receives, and is responsive to, controllingelectrical signals from the control system 190. The optical receiver 282returns measurement signals to the control system 190.

The in-situ metrology system may comprise any instrument configured tomonitor the progress of the GCIB processing. According to oneembodiment, the in-situ metrology system may constitute an opticalscatterometry system. The scatterometry system may include ascatterometer, incorporating beam profile ellipsometry (ellipsometer)and beam profile reflectometry (reflectometer), commercially availablefrom KLA-Tencor Corporation, (One Technology Drive, Milpitas, Calif.95035), or Nanometrics, Inc. (1550 Buckeye Drive, Milpitas, Calif.95035).

For instance, the in-situ metrology system may include an integratedOptical Digital Profilometry (iODP) scatterometry module configured tomeasure process performance data resulting from the execution of atreatment process in the GCIB processing system 100′. The metrologysystem may, for example, measure or monitor metrology data resultingfrom the treatment process. The metrology data can, for example, beutilized to determine process performance data that characterizes thetreatment process, such as a process rate, a relative process rate, afeature profile angle, a critical dimension, a feature thickness ordepth, a feature shape, etc. For example, in a process for directionallydepositing material on a substrate, process performance data can includea critical dimension (CD), such as a top, middle or bottom CD in afeature (i.e., via, line, etc.), a feature depth, a material thickness,a sidewall angle, a sidewall shape, a deposition rate, a relativedeposition rate, a spatial distribution of any parameter thereof, aparameter to characterize the uniformity of any spatial distributionthereof, etc. Operating the X-Y positioning table 253 via controlsignals from control system 190, the in-situ metrology system can mapone or more characteristics of the substrate 252.

In the embodiment shown in FIG. 7, the GCIB processing system 100″ canbe similar to the embodiment of FIG. 5 and further comprise a pressurecell chamber 350 positioned, for example, at or near an outlet region ofthe ionization/acceleration chamber 106. The pressure cell chamber 350comprises an inert gas source 352 configured to supply a background gasto the pressure cell chamber 350 for elevating the pressure in thepressure cell chamber 350, and a pressure sensor 354 configured tomeasure the elevated pressure in the pressure cell chamber 350.

The pressure cell chamber 350 may be configured to modify the beamenergy distribution of GCIB 128 to produce a modified processing GCIB128A′. This modification of the beam energy distribution is achieved bydirecting GCIB 128 along a GCIB path through an increased pressureregion within the pressure cell chamber 350 such that at least a portionof the GCIB traverses the increased pressure region. The extent ofmodification to the beam energy distribution may be characterized by apressure-distance integral along the at least a portion of the GCIBpath, where distance (or length of the pressure cell chamber 350) isindicated by path length (d). When the value of the pressure-distanceintegral is increased (either by increasing the pressure and/or the pathlength (d)), the beam energy distribution is broadened and the peakenergy is decreased. When the value of the pressure-distance integral isdecreased (either by decreasing the pressure and/or the path length(d)), the beam energy distribution is narrowed and the peak energy isincreased. Further details for the design of a pressure cell may bedetermined from U.S. Pat. No. 7,060,989, entitled “Method and apparatusfor improved processing with a gas-cluster ion beam”; the content ofwhich is incorporated herein by reference in its entirety.

Control system 190 comprises a microprocessor, memory, and a digital I/Oport capable of generating control voltages sufficient to communicateand activate inputs to GCIB processing system 100 (or 100′, 100″), aswell as monitor outputs from GCIB processing system 100 (or 100′, 100″).Moreover, control system 190 can be coupled to and can exchangeinformation with vacuum pumping systems 170A, 170B, and 170C, first gassource 111, second gas source 112, first gas control valve 113A, secondgas control valve 113B, beam electronics 130, beam filter 146, beam gate148, the X-scan actuator 160, the Y-scan actuator 162, and beam currentsensor 180. For example, a program stored in the memory can be utilizedto activate the inputs to the aforementioned components of GCIBprocessing system 100 according to a process recipe in order to performa GCIB process on substrate 152.

However, the control system 190 may be implemented as a general purposecomputer system that performs a portion or all of the microprocessorbased processing steps of the invention in response to a processorexecuting one or more sequences of one or more instructions contained ina memory. Such instructions may be read into the controller memory fromanother computer readable medium, such as a hard disk or a removablemedia drive. One or more processors in a multi-processing arrangementmay also be employed as the controller microprocessor to execute thesequences of instructions contained in main memory. In alternativeembodiments, hard-wired circuitry may be used in place of or incombination with software instructions. Thus, embodiments are notlimited to any specific combination of hardware circuitry and software.

The control system 190 can be used to configure any number of processingelements, as described above, and the control system 190 can collect,provide, process, store, and display data from processing elements. Thecontrol system 190 can include a number of applications, as well as anumber of controllers, for controlling one or more of the processingelements. For example, control system 190 can include a graphic userinterface (GUI) component (not shown) that can provide interfaces thatenable a user to monitor and/or control one or more processing elements.

Control system 190 can be locally located relative to the GCIBprocessing system 100 (or 100′, 100″), or it can be remotely locatedrelative to the GCIB processing system 100 (or 100′, 100″). For example,control system 190 can exchange data with GCIB processing system 100using a direct connection, an intranet, and/or the Internet. Controlsystem 190 can be coupled to an intranet at, for example, a customersite (i.e., a device maker, etc.), or it can be coupled to an intranetat, for example, a vendor site (i.e., an equipment manufacturer).Alternatively or additionally, control system 190 can be coupled to theInternet. Furthermore, another computer (i.e., controller, server, etc.)can access control system 190 to exchange data via a direct connection,an intranet, and/or the Internet.

Substrate 152 (or 252) can be affixed to the substrate holder 150 (orsubstrate holder 250) via a clamping system (not shown), such as amechanical clamping system or an electrical clamping system (e.g., anelectrostatic clamping system). Furthermore, substrate holder 150 (or250) can include a heating system (not shown) or a cooling system (notshown) that is configured to adjust and/or control the temperature ofsubstrate holder 150 (or 250) and substrate 152 (or 252).

Vacuum pumping systems 170A, 170B, and 170C can include turbo-molecularvacuum pumps (TMP) capable of pumping speeds up to about 5000 liters persecond (and greater) and a gate valve for throttling the chamberpressure. In conventional vacuum processing devices, a 1000 to 3000liter per second TMP can be employed. TMPs are useful for low pressureprocessing, typically less than about 50 mTorr. Although not shown, itmay be understood that pressure cell chamber 350 may also include avacuum pumping system. Furthermore, a device for monitoring chamberpressure (not shown) can be coupled to the vacuum vessel 102 or any ofthe three vacuum chambers 104, 106, 108. The pressure-measuring devicecan be, for example, a capacitance manometer or ionization gauge.

Referring now to FIG. 8, a section 300 of an ionizer (122, FIGS. 5, 6and 7) for ionizing a gas cluster jet (gas cluster beam 118, FIGS. 5, 6and 7) is shown. The section 300 is normal to the axis of GCIB 128. Fortypical gas cluster sizes (2000 to 15000 atoms), clusters leaving thegas skimmer (120, FIGS. 5, 6 and 7) and entering an ionizer (122, FIGS.5, 6 and 7) will travel with a kinetic energy of about 130 to 1000electron volts (eV). At these low energies, any departure from spacecharge neutrality within the ionizer 122 will result in a rapiddispersion of the jet with a significant loss of beam current. FIG. 8illustrates a self-neutralizing ionizer. As with other ionizers, gasclusters are ionized by electron impact. In this design,thermo-electrons (seven examples indicated by 310) are emitted frommultiple linear thermionic filaments 302 a, 302 b, and 302 c (typicallytungsten) and are extracted and focused by the action of suitableelectric fields provided by electron-repeller electrodes 306 a, 306 b,and 306 c and beam-forming electrodes 304 a, 304 b, and 304 c.Thermo-electrons 310 pass through the gas cluster jet and the jet axisand then strike the opposite beam-forming electrode 304 b to produce lowenergy secondary electrons (312, 314, and 316 indicated for examples).

Though (for simplicity) not shown, linear thermionic filaments 302 b and302 c also produce thermo-electrons that subsequently produce low energysecondary electrons. All the secondary electrons help ensure that theionized cluster jet remains space charge neutral by providing low energyelectrons that can be attracted into the positively ionized gas clusterjet as required to maintain space charge neutrality. Beam-formingelectrodes 304 a, 304 b, and 304 c are biased positively with respect tolinear thermionic filaments 302 a, 302 b, and 302 c andelectron-repeller electrodes 306 a, 306 b, and 306 c are negativelybiased with respect to linear thermionic filaments 302 a, 302 b, and 302c. Insulators 308 a, 308 b, 308 c, 308 d, 308 e, and 308 f electricallyinsulate and support electrodes 304 a, 304 b, 304 c, 306 a, 306 b, and306 c. For example, this self-neutralizing ionizer is effective andachieves over 1000 micro Amps argon GCIBs.

Alternatively, ionizers may use electron extraction from plasma toionize clusters. The geometry of these ionizers is quite different fromthe three filament ionizer described above but the principles ofoperation and the ionizer control are very similar. Referring now toFIG. 9, a section 400 of an ionizer (122, FIGS. 5, 6 and 7) for ionizinga gas cluster jet (gas cluster beam 118, FIGS. 5, 6 and 7) is shown. Thesection 400 is normal to the axis of GCIB 128. For typical gas clustersizes (2000 to 15000 atoms), clusters leaving the gas skimmer (120,FIGS. 5, 6 and 7) and entering an ionizer (122, FIGS. 5, 6 and 7) willtravel with a kinetic energy of about 130 to 1000 electron volts (eV).At these low energies, any departure from space charge neutrality withinthe ionizer 122 will result in a rapid dispersion of the jet with asignificant loss of beam current. FIG. 9 illustrates a self-neutralizingionizer. As with other ionizers, gas clusters are ionized by electronimpact.

The ionizer includes an array of thin rod anode electrodes 452 that issupported and electrically connected by a support plate (not shown). Thearray of thin rod anode electrodes 452 is substantially concentric withthe axis of the gas cluster beam (e.g., gas cluster beam 118, FIGS. 5, 6and 7). The ionizer also includes an array of thin rod electron-repellerrods 458 that is supported and electrically connected by another supportplate (not shown). The array of thin rod electron-repeller electrodes458 is substantially concentric with the axis of the gas cluster beam(e.g., gas cluster beam 118, FIGS. 5, 6 and 7). The ionizer furtherincludes an array of thin rod ion-repeller rods 464 that is supportedand electrically connected by yet another support plate (not shown). Thearray of thin rod ion-repeller electrodes 464 is substantiallyconcentric with the axis of the gas cluster beam (e.g., gas cluster beam118, FIGS. 5, 6 and 7).

Energetic electrons are supplied to a beam region 444 from a plasmaelectron source 470. The plasma electron source 470 comprises a plasmachamber 472 within which plasma is formed in plasma region 442. Theplasma electron source 470 further comprises a thermionic filament 476,a gas entry aperture 426, and a plurality of extraction apertures 480.The thermionic filament 476 is insulated from the plasma chamber 470 viainsulator 477. As an example, the thermionic filament 476 may include atungsten filament having one-and-a-half turns in a “pigtail”configuration.

The section 400 of the gas cluster ionizer comprises anelectron-acceleration electrode 488 having plural apertures 482.Additionally, the section 400 comprises an electron-decelerationelectrode 490 having plural apertures 484. The plural apertures 482, theplural apertures 484, and the plural extraction apertures 480 are allaligned from the plasma region 442 to the beam region 444.

Plasma forming gas, such as a noble gas, is admitted to the plasmachamber 472 through gas entry aperture 426. An insulate gas feed line422 provides pressurized plasma forming gas to a remotely controllablegas valve 424 that regulates the admission of plasma forming gas to theplasma chamber 472.

A filament power supply 408 provides filament voltage (V_(F)) fordriving current through thermionic filament 476 to stimulatethermo-electron emission. Filament power supply 408 controllablyprovides about 140 to 200 A (amps) at 3 to 5 V (volts). An arc powersupply 410 controllably provides an arc voltage (V_(A)) to bias theplasma chamber 472 positive with respect to the thermionic filament 476.Arc power supply 410 is typically operated at a fixed voltage, typicallyabout 35 V, and provides means for accelerating the electrons within theplasma chamber 472 for forming plasma. The filament current iscontrolled to regulate the arc current supplied by the arc power supply410. Arc power supply 410 is capable of providing up to 5 A arc currentto the plasma arc.

Electron deceleration electrode 490 is biased positively with respect tothe plasma chamber 472 by electron bias power supply 412. Electron biaspower supply 412 provides bias voltage (V_(B)) that is controllablyadjustable over the range of from 30 to 400 V. Electron accelerationelectrode 488 is biased positively with respect to electron decelerationelectrode 490 by electron extraction power supply 416. Electronextraction power supply 416 provides electron extraction voltage(V_(EE)) that is controllable in the range from 20 to 250 V. Anacceleration power supply 420 supplies acceleration voltage (V_(ACC)) tobias the array of thin rod anode electrodes 452 and electrondeceleration electrode 490 positive with respect to earth ground.V_(ACC) is the acceleration potential for gas cluster ions produced bythe gas cluster ionizer shown in section 400 and is controllable andadjustable in the range from 1 to 100 kV. An electron repeller powersupply 414 provides electron repeller bias voltage (V_(ER)) for biasingthe array of thin rod electron-repeller electrodes 458 negative withrespect to V_(ACC). V_(ER) is controllable in the range of from 50 to100 V. An ion repeller power supply 418 provides ion repeller biasvoltage (V_(IR)) to bias the array of thin rod ion-repeller electrodes464 positive with respect to V_(ACC). V_(IR) is controllable in therange of from 50 to 150V.

A fiber optics controller 430 receives electrical control signals oncable 434 and converts them to optical signals on control link 432 tocontrol components operating at high potentials using signals from agrounded control system. The fiber optics control link 432 conveyscontrol signals to remotely controllable gas valve 424, filament powersupply 408, arc power supply 410, electron bias power supply 412,electron repeller power supply 414, electron extraction power supply416, and ion repeller power supply 418.

For example, the ionizer design may be similar to the ionizer describedin U.S. Pat. No. 7,173,252, entitled “Ionizer and method for gas-clusterion-beam formation”; the content of which is incorporated herein byreference in its entirety.

The ionizer (122, FIGS. 5, 6 and 7) may be configured to modify the beamenergy distribution of GCIB 128 by altering the charge state of the GCIB128. For example, the charge state may be modified by adjusting anelectron flux, an electron energy, or an electron energy distributionfor electrons utilized in electron collision-induced ionization of gasclusters.

Although only certain embodiments of this invention have been describedin detail above, those skilled in the art will readily appreciate thatmany modifications are possible in the embodiments without materiallydeparting from the novel teachings and advantages of this invention.Accordingly, all such modifications are intended to be included withinthe scope of this invention.

The invention claimed is:
 1. A method for opening a conformal layer atthe bottom of a high aspect ratio contact via on a substrate,comprising: providing a substrate having a first layer with a viapattern formed therein and a second layer conformally deposited on saidfirst layer and within said via pattern, said second layer extendingalong a top surface of said first layer, wrapping over a corner at anentrance to said via pattern, and penetrating into said via patternwhile conforming to the sidewalls and the bottom of said via pattern toestablish a contact via pattern, and measuring initial criticaldimensions (CD) at approximately mid-depth of said contact via patternand at said corner at said entrance; etching through said second layerat the bottom of said contact via pattern to extend said contact viapattern through said second layer and form a contact via while retainingat least part of said second layer on said top surface of said firstlayer, said corner at said entrance to said via pattern, and saidsidewalls of said via pattern, wherein said etching is performed byirradiating said substrate with a gas cluster ion beam (GCIB) accordingto a GCIB etching process; and measuring final critical dimensions (CD)at approximately said mid-depth of said contact via pattern and at saidcorner at said entrance; wherein said etching includes selecting a beamenergy distribution for said GCIB to reduce erosion of a corner profilefor said second layer to a value of 10 nm or less, wherein said erosionof said corner profile is assessed by measuring a difference betweensaid initial and final CDs at said corner at said entrance.
 2. Themethod of claim 1, wherein said selecting a beam energy distributionincludes setting a background gas pressure for an increased pressureregion through which said GCIB passes, or a background gas flow rate foran increased pressure region through which said GCIB passes, or both. 3.The method of claim 2, wherein said GCIB etching process includessetting one or more GCIB properties, and wherein at least one of saidone or more GCIB properties is selected from the group consisting of aGCIB composition, a beam dose, a beam acceleration potential, and a flowrate of said GCIB composition.
 4. The method of claim 1, wherein saidGCIB etching process comprises: holding said substrate securely within areduced-pressure environment; forming a gas cluster ion beam (GCIB) froma pressurized gas comprising an etching gas including carbon (C),hydrogen (H), and a halogen element; accelerating said GCIB to saidreduced-pressure environment; and irradiating said accelerated GCIB ontoat least a portion of said substrate to selectively etch said secondlayer on said substrate.
 5. The method of claim 4, wherein said etchinggas includes a mono-substituted halomethane, a di-substitutedhalomethane, or a tri-substituted halomethane, or any combination of twoor more thereof.
 6. The method of claim 4, wherein said etching gasincludes CHF₃, CHCl₃, or CHBr₃.
 7. The method of claim 4, wherein saidpressurized gas further comprises He, Ne, Ar, Kr, Xe, O₂, CO, CO₂, N₂,NO, NO₂, N₂O, NH₃, F₂, HF, SF₆, or NF₃, or any combination of two ormore thereof.
 8. The method of claim 1, further comprising: selectingone or more target etch process metrics, said one or more target etchprocess metrics including an etch rate of said first layer, an etch rateof said second layer, an etch rate of said substrate, an etchselectivity between said first layer and said second layer, an etchselectivity between said second layer and said substrate, a surfaceroughness of said second layer, a surface roughness of said substrate,an etch profile of said contact via, a difference between initial andfinal CDs of said contact via pattern at said approximate mid-depth, andsaid corner profile of said contact via pattern; and in addition toselecting a beam energy distribution for said GCIB, setting one or moreadditional GCIB properties of a GCIB process condition for operatingsaid GCIB to perform said GCIB etching process and achieve said one ormore target etch process metrics.
 9. The method of claim 8, wherein saidone or more additional GCIB properties of said GCIB process conditioninclude a GCIB composition, a beam dose, a beam acceleration potential,a beam focus potential, a beam energy, a beam angular distribution, abeam divergence angle, a flow rate of said GCIB composition, astagnation pressure, a stagnation temperature, a background gas pressurefor an increased pressure region through which said GCIB passes, or abackground gas flow rate for an increased pressure region through whichsaid GCIB passes.
 10. The method of claim 1, wherein said first layercomprises an oxide.
 11. The method of claim 1, wherein said second layercomprises an oxide-nitride-oxide (ONO) layer.
 12. The method of claim 1,wherein a thickness of said second layer comprises ranges from 20 nm to40 nm.
 13. The method of claim 1, wherein said erosion of said cornerprofile is assessed at a value of 5 nm or less.
 14. The method of claim1, wherein said erosion of said corner profile is assessed at a value of2 nm or less.
 15. The method of claim 1, wherein said etching includesselecting said beam energy distribution for said GCIB or selecting anadditional GCIB process condition for said GCIB etching process toachieve a CD loss having a value of 5 nm or less, said CD loss beingmeasured as the difference between said final CD of said contact viapattern and said initial CD of said contact via pattern at saidapproximate mid-depth.
 16. The method of claim 15, wherein said CD losshas a value of 2 nm or less.
 17. The method of claim 1, wherein saidcontact via has an aspect ratio of 5:1 or greater, said aspect ratiobeing measured as the ratio between a depth of said contact viafollowing said etching and a final CD of said contact via pattern atsaid approximate mid-depth.
 18. The method of claim 17, wherein saidaspect ratio is 10:1 or greater.